device_guard = "// DeviceGuard omitted" # default

if has_tensor_options:
  # kernel is creating a tensor
  if is_cuda_dispatch_key(self.dispatch_key):
    # initialize CUDA on construction of CUDA tensors
    init_cuda = "globalContext().lazyInitCUDA();"
  if f.device_guard:
    if local.use_c10_dispatcher() is UseC10Dispatcher.full:
      device_guard = "const DeviceGuard device_guard(device_or_default(device));"
    else:
      device_guard = "const DeviceGuard device_guard(options.device());"
else:
  # kernel is operating on existing tensors
  if f.device_guard:
    self_args = (a for a in f.func.arguments if a.name == "self")
    # There is precedence for which argument we use to do
    # device guard.  This describes the precedence order.
    candidate_args = itertools.chain(self_args, f.func.out_arguments, f.func.arguments)
    # Only tensor like arguments are eligible
    device_of = next((f'{a.name}' for a in candidate_args if a.type.is_tensor_like()), None)
    if device_of is not None:
      device_guard = f"const OptionalDeviceGuard device_guard(device_of({device_of}));"